One thing I have learned is how critical EXACT location is. Fishermen call it the "spot on the spot". In my experience, canines aren't going to alter their travels very much at all to investigate a set. You have to be very close to their travel line to start with, (contrary to some lure advertisements).
In my area, about the only sign you will find during fall trapping on bare ground are droppings. Visible tracks on dry fields and woods roads are almost non existant, so being able to predict animals movements by judging the EXACT location is critical.
The best example from my own line is a long field that runs north and south with woods bordering it on the north and west sides. There is a diversion ditch running through this field from east to west. The first year I set up at the intersection of the diversion ditch and the woods. Caught a couple of fox, but figured this farm could do better. The next year I studied the area a little more and added another couple of sets to the east along a little weed line that runs the length of the field from north to south. This was less than 50 yards east of the original location. That year, I caught 9 canines in 11 days from the new location with only a coon in the original spot. I am not sure how much better it would have done because on the 11th day the owner spread liquid manure all over that field! This location has continued to produce (although not quite as well as the first year) from year to year. My point here is that the new location was only 50 yards away from a "good spot" [b]and[/b] down wind. I am sure that most of the canines I caught could smell the original sets but didn't go out of their way to investigate.
Another example is this year, where I made a couple of sets at the tip of a classic "point" of weeds running off of a field road and into a ditch. Nothing in a week. Punched in two more sets right at the edge of the tire tracks on the field road only 30 feet from the original set. Two fox in three days. You wouldn't think 30 feet would make much of a difference (especially when lure is being used), but it does.
I guess that my point here is that learning where "general" locations is very important, getting the EXACT location is critical to success.